1. Field of the Invention
The present invention relates to a compound of the formula (I) or its salt and a process for producing the compounds; The compounds have the effect to dilate neophrovascular tracts; ##STR3## wherein represents the formula ##STR4## (wherein R.sup.4 is a hydrogen atom or lower alkylsulfonyl); R.sup.1 is hydrogen, lower alkyl, hydroxyl, halogen, amino, or lower acylamino;
R.sup.2 is hydrogen, lower alkyl, hydroxyl, amino, or lower alkylsulfonylamino; PA1 R.sup.3 is hydrogen, lower alkyl, or hydroxyl; PA1 R is hydrogen or halogen;
with the proviso that when R.sup.1 is hydroxyl, there is no case that all of R.sup.2, R.sup.3 and R are hydrogens, and further with the proviso that when R is hydrogen, A excludes ##STR5## or a salt thereof. (The above definitions in the formula (I) and groups are interpreted to be the same, hereinafter.) The compounds act directly upon dopamine receptor present in renal vascular tracts, and are used as nephrovascular dilators.
This invention relates to amino-substituted tetrahydroisoquinoline derivatives represented by the following general formula (I), ##STR6## or salts thereof, which are compounds useful as medicines; to a process for preparing the same; and to medicines containing the same as active ingredient.
2. Description of the Related Art
The kidney is an important organ which participates in maintaining homeostasis of the cirulatory system. If blood circulation insufficiency occurs in this organ for some causes, renal functions will lower to break up homeostasis of the circulatory system, thus inducing, maintaining or aggravating diseases of circulatory organs, such as hypertension and cardiac insufficiency.
Vasodilators and diuretics have been used for the treatment of these diseases, but no vasodilator is so far known which has a positive effect to dilate renal vascular tracts. It is also known that conventional diuretics tend to upset the balance among electrolytes. Dopamine shows diuretic and nephrovascular dilating effects, but also has unfavorable effects (vasoconstricting and heart-rate increasing effects). In addition, it cannot be orally administered and its effect is not well maintained. Thus, there is no drug presently available which is suited for clinical use.